JPH05329853A - Method and its device of in-mold foam molding - Google Patents

Abstract

PURPOSE:To reduce a cooling time, by a method wherein after heating, foaming and bonding are performed and after water passing through the inside of a mold is drained and removed, a foam-molded product on the inside of a cavity space is cooled by passing cooling water of a chiller through the mold and the cooling water of the chiller passed through the mold is recovered to a drain recovery tank. CONSTITUTION:When heating through water passing is completed, a steam drain valve 6' which has been kept open is closed also, both steam valves 16a, 16b are reopened, a foam-molded body 4a is heated on both side and enters into a both side heating process performing complete burning of the surface of the foam-molded body 4a. After completion of both side heating, the same enters into a cooling process of the foam-molded body. Then when temperatures of the rears of a male mold 1b and female mold 2b come down to the normal temperature of cooling water, cooling is changed over to injection by cold water not exceeding about 10 deg.C by a source of water supply of a chiller. With the construction, the temperatures of the rears of the male mold 1b and female mold 2b are lowered quickly and can be lowered down quickly to the vicinity of about 10 deg.C in a short time, through which a temperature of a core part of a foam-molded body 4a can be lowered quickly further.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-mold foam molding method for a synthetic resin foam molded article. More specifically, it relates to an in-mold foam molding method capable of economically using chiller cooling water at 15 ° C. or less and an in-mold foam molding apparatus capable of economically supplying the chiller cooling water.

[0002]

2. Description of the Related Art The most widely used one in fusion foam molding using pre-expanded granules is expanded polystyrene (hereinafter referred to as E
It is abbreviated as PS).

In the case of foam molding of EPS, after heat-foam fusion is performed, in the cooling step, vacuum cooling or the like is carried out to effectively utilize the latent heat of vaporization of water that has penetrated into the bubbles of the pre-expanded granules of EPS. The molding could be completed in a relatively short cycle. This is because the foamed film of the fused foamed particles is rich in water vapor permeability and has a property of easily evaporating and passing water under vacuum reduced pressure.

However, recent synthetic resin foams are
Many attempts have been made to develop it into various raw material resins, and under such circumstances, the in-mold foam molding method adapted to EPS as described above cannot be generally used, and resin raw materials cannot be used. There is a demand for a molding method adapted to the characteristics of the above.

For example, the water vapor permeation resistance of the foamed film of the pre-expanded particles is improved to suppress the permeation of the foaming gas existing inside the pre-expanded particles so that the characteristics of the foaming gas are maximized and the heat insulation is performed. There is a case where the property is enhanced or the buffer property is enhanced. In such a case, a cooling method such as the above-described vacuum cooling has a small cooling effect, requires a long cooling time, lowers productivity, and is extremely economically disadvantageous.

[0006]

DISCLOSURE OF THE INVENTION The present invention, in a method and apparatus for molding synthetic resin foam particles 4 in a mold, can increase the water vapor permeability of a bubble film of the particles 4 from the characteristics of the raw material resin. If it is not present, the cooling time during in-mold molding is effectively reduced.

Generally, the normal cooling water used for cooling the foamed molded product is about 30 ° C. on average, and it may reach 50 ° C. or more by recycling, and the cooling time is reduced by using normal water. Things get more difficult. However, if chiller water having an excellent cooling effect is used during the entire cooling process, the cooling rate can be increased, but the cooling cost is too high.

[0008]

Therefore, in the method of the present invention, after the heat-foaming fusion is performed, water is usually added to the molds 1 and 2.
Water to the molds 1 and 2 to cool them to near room temperature, and then remove the water flowing in the molds 1 and 2 by drainage, and then pass the chiller cooling water to the molds 1 and 2. The foamed molded product 4a in the cavity space 3 is cooled and the chiller cooling water that has passed through is collected in the drain collection tank 22.

In order to actually carry out the above method, the in-mold foam molding apparatus of the present invention is provided in a movable mold 1 and a stationary mold 2 having steam chambers 1d and 2d therein, and a mold cavity space 3. A cooling device using ordinary water for cooling the molds 1, 2 heated by the steam press-fitted into the steam chambers 1d, 2d for foaming the filled synthetic resin pre-expanded granules 4 to normal temperature, A chiller cooling device for supplying chiller cooling water for further cooling the foam-molded product 4a in the mold cavity space 3 that has been heat-foamed and fused. As a result, the foamed molded body 4a can be cooled quickly and at low cost.

The chiller cooling water in the present invention means water having a temperature higher than 0 ° C. and lower than 15 ° C. If the temperature is lower than 0 ° C, it becomes impossible to circulate in the apparatus due to freezing, and if the temperature exceeds 15 ° C, the cooling effect is reduced. As described above, normal water has an average temperature of 30 ° C., and sometimes exceeds 50 ° C. in some cases. Here, the purpose of draining and removing normal water
Water that has been passed through in the first-stage cooling process that cools the molds 1 and 2 that have been heated to a high temperature in the heat-foaming and fusion-bonding process, and that has reached a high temperature due to heat exchange with the molds 1 and 2 is the second-stage cooling process. This is to prevent unnecessarily increasing the recovery temperature of the chiller cooling water by being mixed with the chiller cooling water that is passed by. The purpose of collecting the chiller cooling water that has been passed is to increase the temperature of the chiller cooling water that has been passed in order to further lower the temperature of the molds 1 and 2 that have already been cooled to room temperature in the first cooling step. This is because it is relatively small and more advantageous than newly cooling ordinary water to 15 ° C or lower.

[0011]

The present invention will be described in detail below with reference to the illustrated embodiments. FIG. 2 is a schematic cross-sectional view of the main part of the foam molding machine, in which the fixed die 2 is mounted on the fixed die plate 7, and the movable die plate 9 reciprocates on the tie bars 8 attached to the four corners of the fixed die plate 7. The movable die 1 is mounted on the movable die plate 9 so as to be slidable.

Further, a cylinder plate 10 is attached to the end of the tie bar 8 on the back of the movable die 1, and the movable die plate 9 is reciprocated together with the movable die 1 by a drive cylinder 11 attached to the cylinder plate 10. I am exercising. A filler 12 for supplying the pre-expanded particles 4 to the cavity space 3 is mounted on the back surface of the fixed mold 2, and the hopper storing the pre-expanded particles 4 in the filler 12 is mounted.
13 are connected.

Next, the structure of the molds 1 and 2 will be described.
The molds 1 and 2 are the same on the fixed side and the moving side.
9, the mold bodies 1a and 2a, the male mold 1b and the female mold 2b forming the cavity space 3, the mold bodies 1a and 2a and the female / male mold 1
b, 2b is a hollow body configured with a heat insulating connection plate 1c, 2c that connects the entire circumference, the hollow portion is a steam chamber 1d, 2d, the mold body 1a, 2a steam pipe 14a, 14b is connected to steam drain pipes 5a 'and 6b' which are steam outlets and chiller recovery drain pipes 5a and 6b which are chiller cooling water recovery ports. The steam drain valve 5 ′, 6b ′ to the steam drain piping 5a ′, 6b ′,
6'is installed, and chiller drain valves 5 and 6 are installed in the chiller recovery drain pipes 5a and 6a. A large number of steam ejection small holes 1e, 2e are bored in the female / male dies 1b, 2b, and the steam introduced into the molds 1, 2 passes through the steam ejection small holes 1e, 2e and inside the cavity space 3. It is designed to squirt (or pass).

Steam piping 14 derived from a steam supply source 15
Is branched and each branch pipe 14a, 14b is moved to the mold 1
To the fixed mold 2 and steam valves 16a and 16b are attached to the respective branch pipes 14a and 14b.

The steam branch pipes 14a and 14b have respective steam chambers 1
Equipped with pressure gauges 17 and 18 for displaying the vapor pressure in d and 2d. The pressure gauges 17 and 18 are equipped with a pressure setting device, and heating control is performed by the set pressure in the steam chambers 1d and 2d.

Next, the cooling device will be described with reference to FIG. The chiller cooling device is a chiller unit 20, a chiller tank 21,
Chiller drain recovery tank 22, chiller water supply valves 23a, 23b
And a piping system that connects them,
On the other hand, a cooling device using normal water has a normal water supply valve.
It is roughly composed of 24a, 24b and a piping system connecting them.

Cooling water injection pipes 25a, 25b are arranged in the steam chambers 1d, 2d of the molds 1, 2 and are connected to the cooling water pipes 26a, 26b. For the cooling water pipes 26a and 26b, the normal water pipe 27
a, 27b and chiller water pipes 28a, 28b are connected, so that switching between normal water and chiller water is switched by the chiller water supply valves 23a, 23b and the normal water supply valves 24a, 24b respectively installed. Is becoming

The chiller water pipes 28a and 28b are connected to the chiller tank 21.
The chiller water stored in the chiller tank 21 is supplied to the molds 1 and 2.

A chiller unit 20 is connected to the chiller tank 21, and chiller cooling water cooled by the chiller unit 20 is supplied to the chiller tank 21 as needed. A drain collection tank 22 is connected to the chiller unit 20 via a pump 30, and the collected drain is reused as chiller water, and at the same time, the shortage is connected to the chiller drain collection tank 22 by a water supply pipe.
Water is supplied from 29. The temperature of the chiller water supplied from the chiller unit 20 depends on the setting, but in this embodiment, the temperature was set to about 10 ° C in consideration of efficiency.

The hot water drain by steam heating and the cooling drain by normal cooling water have a high temperature, are connected to the steam drain pipes 5a ', 6b' through other steam drain valves 5 ', 6', and are discharged to the outside of the machine. To be removed. Meanwhile, the chiller drain recovery tank 22
Are connected to the chiller recovery pipes 5a and 6b respectively,
Only the used chiller cooling water is collected through the chiller drain valves 5 and 6.

The chiller drain recovery tank 22 and the chiller tank 21 have a heat insulating structure in which a heat insulating material is attached to the outer circumference of the tank. The chiller water pipes 28a and 28b that connect the chiller tank 21 to the molds 1 and 2 are also pipes that have been subjected to bar heat treatment such as rubber hoses.

The chiller tank 21, the chiller unit 20 and the chiller drain recovery tank 22 are connected by pipes 31 and 32, respectively, and valves 33 and 34 are interposed between them. The valves 33 and 34 are used to shut off when water is supplied from the chiller tank 21 to the molds 1 and 2, and to pressurize the chiller tank 21 with air.

With the chiller system circuit, the chiller water cooled by the chiller unit 20 flows back through the chiller unit 20 → chiller tank 21 → chiller drain recovery tank 22 and a small recycling passage and drain valves 5, 6 → chiller drain recovery tank 22. → Chiller unit 20 → Chiller tank 21 → A large recycling passage that recycles molds 1 and 2 enables effective recovery of chiller cooling water without mixing cooled water with hot water discharged from molds 1 and 2. You can do it.

The operation of the embodiment of the present invention will be described. First, the drive cylinder 11 is operated to close the mold by leaving a gap between the molds 1 and 2 such that the pre-foamed particles 4 do not pop out.
By operating the filler 12, the pre-expanded particles 4 of synthetic resin or the like having a very low water vapor permeability of the bubble film of the particles 4 are filled in the cavity space 3 by air-feeding air. The empty air flows out from the gap between the molds 1 and 2.

Steam drain valve for moving mold 1 and fixed mold 2
5 ′ and 6 ′ are opened, and both steam valves 16a and 16b are opened to pass steam through the molds 1 and 2 to heat the molds. Naturally, the chiller drain valves 5 and 6 are closed until the chiller cooling operation.

When the heating of the mold is completed, the steam drain valve 5'of the steam chamber 1d is closed, and the steam drain valve 6a of the steam chamber 2d is opened, and the steam valve 14a is fully opened (at this time, other steam valves 14b is closed.), The steam is passed from the steam chamber 1d through the gap between the pre-expanded particles 4 filled in the cavity space 3 to the steam chamber 2d.
And then discharge through drain valve 6 '.

When the flowing steam pressure in the steam chamber 1d rises according to the thermal expansion of the pre-expanded granules 4 in the cavity space 3 and the flowing steam pressure reaches the set value of the pressure gauge 18, the steam valve 16a is turned on. Close to complete flow heating. In addition, fixed mold 2 is used for flow heating.
Sometimes done from the side.

As a result, the heat is sufficiently transmitted to the center of the cavity space 3 to promote the internal fusion of the foam molding 4a.

When the flow-through heating is completed in this way, the steam drain valve 6'which has been opened is also closed (the steam drain valve 5'is closed from the beginning), and both steam valves 16a, 1.
Both sides of 6b are opened again to heat the foamed molded body 4a from both sides, and a double-sided heating step is performed in which the surface of the foamed molded body 4a is baked. The vapor pressure during double-sided heating is controlled so as to rise to a set pressure. Further, the heating time for double-sided heating is controlled by a timer. The above-mentioned double-sided heating balances the fusion bonding of the surface of the molded body 4a over the core portion and each surface portion.

After completion of such double-sided heating, the step of cooling the foamed molded article is started.

In the step of cooling the foamed molded product, the foaming gas trapped in the bubble film of the expanded particles does not escape at all due to the strong water vapor permeation resistance of the bubble film. Therefore, even if a cooling promotion method that is effective in the case of EPS, such as vacuum cooling and multi-stage cooling, is applied, there is almost no effect.

As a result of the earnest research by the present inventor, the only factor that promotes cooling is the temperature difference ΔT between the core temperature of the foamed molded body 4a and the male / female molds 1b and 2b forming the molded body. I knew it was. Since the synthetic resin foam used in this example has a large heat insulating property, the only way to remove the heat energy trapped inside the foamed molded body is by using a low temperature heat medium and conducting it by heat conduction. .. We pursued a combination of methods to lower the internal temperature of the heat-sealed foamed molded article by heat conduction by a low-temperature heat medium.

In the cooling diagram of FIG. 3, the horizontal axis represents time and the vertical axis represents temperature. First, the normal cooling water of about 30 ° C. is sprayed from the back surfaces of the male mold 1b and female mold 2b in a shower shape to The temperatures of the back surfaces of the mold 1b and the female mold 2b are lowered to remove the heat of the foamed molded body 4a. When the temperatures of the back surfaces of the male mold 1b and the female mold 2b have dropped to the normal cooling water temperature, the injection is switched to cold water injection of 10 ° C. or less by the chiller water source. By doing so, the temperature of the back surfaces of the male mold 1b and the female mold 2b can be rapidly lowered to a temperature of about 10 ° C. in a short time, and the core temperature of the foam 4a can be further rapidly lowered. (Solid line in Figure 3)

If the chiller water source is not used and the cooling is continued only with normal water of about 30 ° C., the cooling gradient becomes small when the temperature difference from the core temperature reaches about 50 ° C.,
It takes a very long time to lower the core temperature of the foam (4a), which is not practical. In the present invention (shown by a thick solid line) in FIG. 3, cooling was completed in 120 seconds, but in the conventional method using normal water (thin broken line), it took more than 3 minutes.
On the contrary, when a chiller water source of about 10 ° C. is used from the beginning, the cooling cost is high even though the cooling rate is fast, and the temperature difference is abrupt, so that the heat distortion of the mold also has an effect.

In FIG. 3, when the temperature of the back surface of the female mold 2b is lowered to about 35 ° C. by normal water cooling, chiller cooling is started with chiller water of 10 ° C., and the back surface temperature of the female mold 2b is reduced to 20 ° C.
The temperature is rapidly lowered to near 0 ° C., and the chiller water is cooled for about 10 seconds, and then the chiller water is cooled, and then the chiller water is cooled again. By repeating the chiller cooling and the cooling, the chiller cooling that is the most rapid and requires the least cooling cost is performed.

The costs were compared when the chiller cooling water was recovered and when it was not. The comparative conditions are that the normal water used is 30 ° C., the chiller cooling water used is 10 ° C., and the recovered chiller cooling water is 14 ° C. When chiller cooling water was collected, the power consumption was 3.7 kW / h, whereas when chiller cooling water was not collected, it was 15 kW / h. Can be deleted.

As described above, by combining the normal water source and the chiller water source and the method of chilling the drain in the case of chiller cooling (large recycling or small recycling), the core temperature of the foamed molded article can be effectively reduced in a short time. It can be lowered with and a great cooling effect can be achieved.

[0038]

As described above, the method and apparatus of the present invention can achieve a reasonable reduction of the mold temperature even when the cooling effect by the cooling method such as vacuum cooling is small, whereby the foamed molded article can be produced. Cooling can be done quickly and cheaply.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a cooling system of a foam molding machine according to the present invention.

FIG. 2 is a schematic sectional view of a foam molding machine according to the present invention.

FIG. 3 is a cooling curve of the foamed molded product according to the present invention.

[Explanation of symbols]

1 ... Moving mold 1a ... Mold main body 1b ... Male mold 1c ... Thermal insulation connecting plate 1d ... Moving side steam chamber 1e ... Steam ejection small hole 2 ... Fixed mold 2a ... Mold main body 2b ...
Female mold 2c ... Insulation connection plate 2d ... Fixed-side steam chamber 2e ... Steam ejection small hole 3 ... Cavity space 4 ... Synthetic resin pre-expanded granules 4a ... Synthetic resin foam molding 5
Chiller drain valve 5 '... Steam outlet (steam drain valve) 6 ... Chiller drain valve 6' ... Steam outlet (steam drain valve) 20 ... Chiller unit 21
Chiller tank 22 Chiller drain recovery tank 23a, 23b Chiller water supply valve

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[Procedure amendment]

[Submission date] June 7, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title: In-mold foam molding method and apparatus

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuo Miura 1-1 Hirata Nakamachi, Suzuka City, Mie Prefecture Asahi Kasei Co., Ltd. 1 Toyo Kikinzoku Kinzoku Co., Ltd. (72) Inventor Hidehiko Yamamoto 523 No. Nishinoyama, Fukusato, Futami-cho, Akashi-shi, Hyogo 1 Toyo Kikinzoku Kinzoku Co., Ltd.

Claims (2)

[Claims] 1. Pre-foamed particles of synthetic resin are filled in a cavity space formed between a closed moving mold and a fixed mold, and steam is introduced into steam chambers of the moving mold and the fixed mold. To complete the heat-foaming fusion of the pre-expanded particles in the cavity space, then pass normal water through the mold to cool the mold to near room temperature, and then pass through the mold. A mold characterized in that after water and water are drained off, chiller cooling water is passed through a mold to cool the foamed molded product in the cavity space, and the chiller cooling water passed through is collected in a drain recovery tank. Inner foam molding method. 2. A moving mold and a fixed mold having a steam chamber inside, and heating by steam injected into the steam chamber for foam molding of synthetic resin pre-expanded granules filled in the mold cavity space. Water supply pipe for cooling the formed mold to room temperature, and a chiller cooling for cooling the foam-molded product heated and foamed and fused in the mold cavity space after cooling the mold with normal water. An in-mold foam molding apparatus comprising a chiller cooling device for water supply and recovery.